1. Field of the Invention
This invention relates to an apparatus for the straightening of weft threads pulled in oblique and/or arcuate distortion in the textile fabric and consists of a number of flexible rods. These form in uniform circular distribution spaced around a shaft, a roller shell. While the rods are held in their center through a disk disposed on the shaft at a constant radial distance from the center axis of the roller shell, the rods are held near their ends at a variable radial distance from the center axis of the roller shell through a sleeve mounted for axial displacement on the shaft.
2. Prior Art
Such an apparatus is known from German Pat. No. DE-PS 525 491. In that apparatus the axial displacement of each sleeve occurs through a handwheel, the hub of which, with female thread, sits on the shaft with male thread in zones.
Apart from the fact that with the known device essentially only symmetrically distorted weft threads can be straightened in the textile fabric, the shell formed by the flexible rods cannot be deformed while the apparatus is in operation. Upon rotation of the handwheel, in fact, the entire roller shell will rotate unless a corresponding counter-moment is exerted, so that axial displacement of the sleeve does not occur and hence there is no deformation of the roller shell. Nor can the necessary counter-moment be supplied by the textile fabric, because the cloth tension normal in the practice is not sufficient for this. Instead, with every attempt at correction, the shell will slip relative to the fabric, and therefore the required distortion of the shell form will not come about and the desired straightening effect will not occur.
Another disadvantage of the known apparatus results from the rigid attachment of the rods in their center. With this method of attachment, the rods must have an especially great elasticity so that they can be deformed to the extent that even considerable weft thread distortions can be straightened. With the elasticity thus required for the rods, there is danger, however, that they will flex too much under the cloth tension, and this, too, has an adverse effect on the straightening action. If, on the other hand, the rods are so rigid that they are not deformed by the web traction, a rigid attachment in the center of the rods leads to an undesired turning point, so that at best obliquely placed S-shaped weft thread distortions can be straightened therewith, but not the usual slantwise distortions.
It is the object of the invention to improve an apparatus of the initially described kind in such a way that the rods forming the roller shell can reliably be brought, during operation, into the required form for the straightening of weft threads pulled in oblique and/or arcuate distortions.